1. Field of the Invention
The present invention relates to improvements of a thermal transferring printing method, and it particularly relates to a thermal transferring printing method suitable to a recording medium of which a surface has unevenness to print thereon.
2. Description of the Related Art
As is well known, a thermal transferring printing apparatus is used to print an ink pattern such as a picture or letters on a recording medium by thermally transferring hot-melt or hot-sublimable ink coated on an ink sheet to the recording medium by heating the ink sheet with a thermal head. However, it poses a problem that a recording medium having surface unevenness (rough surface) can not be employed in the apparatus because of degradation of printing quality due to an insufficient contact of the ink with the recessed portions of the unevenness of the recording medium.
As countermeasure of the insufficient contact, a hot-melt ink having high fluidity or a dot plate formed in accordance with the printing contents is employed as well as applying a large contact force with the thermal head. However, an acceptable result is not obtained yet.
In order to eliminate the above problem, there is proposed a thermal transferring printing method in xe2x80x9cJapan Hardcopy ""92xe2x80x9d, as shown in FIG. 1.
FIG. 1 is a side view showing a general construction and an operation of a thermal transfer printer in a prior art.
Referring to FIG. 1, after thermally transferring an ink pattern 101 onto a surface of a soft platen roller 103 from an ink sheet 100 with a thermal head 102, the ink pattern 101 on the platen roller 103 is printed by pressing the platen roller 103 onto a surface of a recording medium 104 having an uneven surface to be printed.
In the above method, however, when using high fluidity ink, there are problems that the ink is liable to flow out from the printed ink pattern on the recording medium when the recording medium has a smooth surface in particular, and it is difficult to superpose many colors of ink on the recording medium at the same time. In addition, a printing of a picture having gradation is also difficult.
Accordingly, a general object of the present invention is to provide methods for transferring hot-melt ink to a recording medium in which the above disadvantages have been eliminated.
A specific object of the present invention is to provide a method for thermally transferring an ink pattern to a recording medium, comprising the steps of, preparing an ink sheet provided with a hot-melt and/or hot-sublimable ink layer thereon and a transparent material sheet provided with transparent hot-melt material layer thereon, thermally producing an ink pattern on the transparent hot-melt material layer of the transparent material sheet by heating the hot-melt and/or hot-sublimate ink layer with a thermal head, and thermally transferring the ink pattern produced on the transparent hot-melt material layer to the recording medium together with the transparent hot-melt material layer.
An another specific object of the present invention is to provide a method for thermally transferring hot-melt and/or hot-sublimable ink to a recording medium, comprising the steps of, preparing an ink sheet having at least a transparent hot-melt material frame layer and a hot-melt and/or hot-sublimable ink frame layer thereon, thermally transferring the transparent hot-melt material frame layer onto a surface of a platen roller, thermally producing an ink pattern on the transferred transparent hot-melt frame layer on the platen roller by heating the transparent hot-melt and/or hot-sublimable ink frame layer with a thermal head, and thermally transferring the ink pattern produced on the transparent hot-melt material layer to the recording medium together with the transparent hot-melt frame layer.
Other objects and further features of the present invention will be apparent from the following detailed description.